Table of ContentsView AllTable of ContentsObesity and FertilityWhat Research SaysCombination PillsAlternate DosingBariatric Surgery CautionOther OptionsTalking With a Healthcare Provider
Table of ContentsView All
View All
Table of Contents
Obesity and Fertility
What Research Says
Combination Pills
Alternate Dosing
Bariatric Surgery Caution
Other Options
Talking With a Healthcare Provider
It had long been suggested that living withoverweight or obesitymight undermine the effectiveness ofbirth control pillsand otherhormonal contraceptives, leading tounplanned pregnancy. It is true that excess body weight can pose health concerns to women for many reasons, but more recent research suggests that decreased efficacy of hormonal birth control may not be one of them.
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Body mass index (BMI) is calculated from a person’s weight and height and provides a reasonable indicator of obesity and its associated health risks.
BMI is a flawed measure because it does not take into account factors such as body composition, ethnicity, sex, race, and age. Still, it is widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.
By definition, obesity is a body mass index (BMI) of 30 or greater, whereas a BMI of between 25 and 29.9 is classified as overweight.
Among them, women with obesity are known to be three times more likely to experience infertility due to hormonal disruptions that impair menstruation and ovulation.
Given this, it seems backwards that birth control pills designed to prevent pregnancy are assumed to be less effective in the very women who are more likely to experience infertility.
Research has long been conflicted on these issues, and only recently have scientists begun to test the hypothesis in a more qualitative way.
Birth Control Effectiveness and Comparisons
Evolution of Research
Much of the confusion surrounding the efficacy of birth control pills in women living with obesity stemmed from earlier research that compared BMI values to pregnancy rates. On their face, findings were often quite compelling.
For instance, a 2010 review in the journalObstetrics & Gynecology, which involved 39,531 women and 11 clinical trials, concluded that heavier women were statistically at a higher risk of unplanned pregnancy while on the pill than women of healthy weight.
However, a closer look at the studies revealed inconsistencies in some of the findings. Among them, some studies suggested that higher weight, not higher BMI, was associated withcontraceptive failure. Others found no such link between weight and unplanned pregnancy.
In fact, of the 11 studies reviewed, only four concluded that BMI was linked to a higher risk of contraceptive failure in women living with overweight or obesity.
Differences in study populations, methods, materials, measures, and controls made it difficult to draw any consistent conclusions other than to say that weightmayplay a role in contraceptive failure rates. Or it may not.
10 Questions to Ask When Choosing Birth Control
Study Shows No Loss of Effect
Of the 150 women who took the pill consistently, three of the 96 healthy-weight women ovulated (meaning that the treatment failed). By comparison, only one of 54 women with obesity experienced such failure. The failure rates were statistically comparable, meaning that obesity played no part in them.
The one factor that did influence contraceptive efficacy was treatment adherence. According to the investigators, the failures were linked to inconsistent dosing rather than BMI or any other weight or metabolic factor. Other studies have supported these findings, albeit with limitations.
A 2016 review published in theCochrane Database of Systematic Reviews(involving 17 studies and 63,813 women) concluded that there was no association between BMI or weight and the effectiveness of hormonal contraceptives.
That is not to suggest, however, thatallhormonal contraceptives are equally effective in heavier women. There is, in fact, evidence that certaincombination birth control pillsmay underperform in women living with obesity or overweight status and lead to an unplanned pregnancy.
Types of Combination Birth Control Pills
Combination Pill Concerns
Combination birth control pills, comprised of different forms of estrogen andprogestin, are generally safe and effective in women with obesity. These include pills containing the synthetic estrogen ethinyl estradiol andprogestin medicationslike drospirenone, levonorgestrel, norethindrone acetate, or norgestimate.
Of the available combinations, there is evidence that birth control pills containing ethinyl estradiol and norethindrone acetate may be twice as likely to fail in women with a BMI over 25 compared to women of normal weight.
The reasons for this are not entirely clear, although some experts suggest that obesity may alter the clearance orhalf-lifeof norethindrone, slowing the rate at which the drug reaches therapeutic levels in the blood.
With that said, there is no evidence of this occurring when norethindrone is taken on its own (inprogestin-only “mini-pills”), leaving the theory largely proven.
Where there is agreement is that research into the effectiveness of birth control pills in women with obesity is sorely lacking. Rarely are heavier women included in pill efficacy studies and, if they are, their weight is hardly ever factored into the results.
Because of this, manufacturers of Lo Loestrin (ethinyl estradiol and norethindrone tablets) and Generess (ethinyl estradiol and norethindrone chewable) have decided to step out in front of the controversy and warn consumers that their drugs' “safety and efficacy in women with BMI over 30 kg/m2 has not been evaluated.”
How to Start Birth Control Pills
Alternate Dosing Strategies
There are currently no guidelines on the use of birth control pills in women living with obesity or overweight status. There are, however, some experts who endorse thecontinuous use of low-dose birth control pills; i.e., the pill is taken every day (rather than in cycles) to completely suppress menstruation.
Others suggest that high-dose birth control pills taken cyclically, as is typical, should be used in place of low-dose contraceptives in these groups.
In both cases, there is evidence that the strategies offered higher sustained blood hormone levels in women with BMIs over 30. What is lacking, however, is any proof that taking continuous or high-dose birth control pills if you live with obesity will result in any better or worse outcomes compared to women of healthy weight.
Even the researchers contend that the main factor affecting contraceptive failure rates was not weight or medication dosages but poor treatment adherence. As such, the benefits of a dose adjustment may be more presumed than real insofar as weight is concerned.
And there are also risks to consider. For example, the use of birth control pills in women living with obesity is linked to an increased risk ofvenous thromboembolism(blood clots in the deep veins of the leg, groin, or arm).It is unknown if higher doses might increase that risk.
It is also yet to be established how safe continuous oral contraceptives are over the long term.
The Facts About Birth Control Failure Rates
Weight loss is not a means of contraception. However, it may theoretically improve the effectiveness of oral contraceptives. To this end, some women with obesity have turned tobariatric surgeryas a means to achieve rapid, “safe” weight loss.
While the surgery offers benefits to women with BMIs over 40, it is more likely than not to reduce, rather than improve, the effectiveness of oral contraceptives.
Preventing Birth Control Failure
Other Birth Control Options
If you live with obesity or overweight status and are concerned about the effectiveness of birth control pills in preventing pregnancy, there are other options you can explore, some of which have proven effective in women with higher BMIs.
In place of oral contraceptives, you may want to consider these hormonal options:
Non-hormonal barrier birth control options include:
Permanent means of birth control include:
If you have a larger body and are worried about whether the pill will fail you, speak with agynecologist.
They can walk you through other methods of birth control if there are reasonable medical concerns or you would simply feel more comfortable changing your method of contraception. Some options may be more appropriate for you than others.
With that said, the failure of the pill usually has more to do with poor adherence—missed doses, inconsistent dosing—that your weight or waist size. If you aren’t taking your birth control pills as you should, ask your gynecologist for tips and advice on how to improve your adherence.
A Word From Verywell
According to the National Center for Health Statistics, more than one-third of adults in the United States have obesity. Of them, 44.7% are women between the ages of 20 and 39. In some racial and ethnic groups, including Hispanics and African Americans, women were more likely to be living with obesity compared to men.
All this to say, if you live with obesity or overweight status, you are not alone. While you may hear about quick-fix solutions, remember that fad diets rarely work over the long term and may cause more harm than good. If you intend to lose weight, do so safely with exercise and a healthy, balanced diet.
9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Silvestris E, De pergola G, Rosania R, Loverro G.Obesity as disruptor of the female fertility.Reprod Biol Endocrinol.2018;16(1):22. doi:10.1186/s12958-018-0336-zLopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM.Hormonal contraceptives for contraception in overweight or obese women.Obstet Gynecol.2010;116(5):1206-7. doi:10.1097/AOG.0b013e3181f81ccfWesthoff CL, Torgal AH, Mayeda ER, et al.Ovarian suppression in normal-weight and obese women during oral contraceptive use: a randomized controlled trial.Obstet Gynecol.2010;116(2 Pt 1):275-83. doi:10.1097/AOG.0b013e3181e79440Lopez LM, Bernholc A, Chen M, et al.Hormonal contraceptives for contraception in overweight or obese women.Cochrane Data System Rev.2016 Aug 18:(8):CD008452. doi:10.1002/14651858.CD008452.pub4Robinson JA, Burke AE.Obesity and hormonal contraceptive efficacy.Womens Health (Lond).2013;9(5):453-66. doi:10.2217/whe.13.41Mody SK, Han M.Obesity and contraception.Clin Obstet Gynecol.2014;57(3):501-7. doi:10.1097/GRF.0000000000000047Solymoss S.Risk of venous thromboembolism with oral contraceptives.CMAJ. 2011;183(18):E1278-9. doi:10.1503/cmaj.111614Hee L, Kettner LO, Vejtorp M.Continuous use of oral contraceptives: an overview of effects and side-effects.Acta Obstet Gynecol Scand.2013;92(2):125-36. doi:10.1111/aogs.12036Hales CM, Carroll MD, Fryar CD, Ogden CL.Prevalence of obesity among adults and youth: United States, 2015-2016.NCHS Data Brief. 2017 Oct;288:1-7.
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Silvestris E, De pergola G, Rosania R, Loverro G.Obesity as disruptor of the female fertility.Reprod Biol Endocrinol.2018;16(1):22. doi:10.1186/s12958-018-0336-zLopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM.Hormonal contraceptives for contraception in overweight or obese women.Obstet Gynecol.2010;116(5):1206-7. doi:10.1097/AOG.0b013e3181f81ccfWesthoff CL, Torgal AH, Mayeda ER, et al.Ovarian suppression in normal-weight and obese women during oral contraceptive use: a randomized controlled trial.Obstet Gynecol.2010;116(2 Pt 1):275-83. doi:10.1097/AOG.0b013e3181e79440Lopez LM, Bernholc A, Chen M, et al.Hormonal contraceptives for contraception in overweight or obese women.Cochrane Data System Rev.2016 Aug 18:(8):CD008452. doi:10.1002/14651858.CD008452.pub4Robinson JA, Burke AE.Obesity and hormonal contraceptive efficacy.Womens Health (Lond).2013;9(5):453-66. doi:10.2217/whe.13.41Mody SK, Han M.Obesity and contraception.Clin Obstet Gynecol.2014;57(3):501-7. doi:10.1097/GRF.0000000000000047Solymoss S.Risk of venous thromboembolism with oral contraceptives.CMAJ. 2011;183(18):E1278-9. doi:10.1503/cmaj.111614Hee L, Kettner LO, Vejtorp M.Continuous use of oral contraceptives: an overview of effects and side-effects.Acta Obstet Gynecol Scand.2013;92(2):125-36. doi:10.1111/aogs.12036Hales CM, Carroll MD, Fryar CD, Ogden CL.Prevalence of obesity among adults and youth: United States, 2015-2016.NCHS Data Brief. 2017 Oct;288:1-7.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Silvestris E, De pergola G, Rosania R, Loverro G.Obesity as disruptor of the female fertility.Reprod Biol Endocrinol.2018;16(1):22. doi:10.1186/s12958-018-0336-zLopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM.Hormonal contraceptives for contraception in overweight or obese women.Obstet Gynecol.2010;116(5):1206-7. doi:10.1097/AOG.0b013e3181f81ccfWesthoff CL, Torgal AH, Mayeda ER, et al.Ovarian suppression in normal-weight and obese women during oral contraceptive use: a randomized controlled trial.Obstet Gynecol.2010;116(2 Pt 1):275-83. doi:10.1097/AOG.0b013e3181e79440Lopez LM, Bernholc A, Chen M, et al.Hormonal contraceptives for contraception in overweight or obese women.Cochrane Data System Rev.2016 Aug 18:(8):CD008452. doi:10.1002/14651858.CD008452.pub4Robinson JA, Burke AE.Obesity and hormonal contraceptive efficacy.Womens Health (Lond).2013;9(5):453-66. doi:10.2217/whe.13.41Mody SK, Han M.Obesity and contraception.Clin Obstet Gynecol.2014;57(3):501-7. doi:10.1097/GRF.0000000000000047Solymoss S.Risk of venous thromboembolism with oral contraceptives.CMAJ. 2011;183(18):E1278-9. doi:10.1503/cmaj.111614Hee L, Kettner LO, Vejtorp M.Continuous use of oral contraceptives: an overview of effects and side-effects.Acta Obstet Gynecol Scand.2013;92(2):125-36. doi:10.1111/aogs.12036Hales CM, Carroll MD, Fryar CD, Ogden CL.Prevalence of obesity among adults and youth: United States, 2015-2016.NCHS Data Brief. 2017 Oct;288:1-7.
Silvestris E, De pergola G, Rosania R, Loverro G.Obesity as disruptor of the female fertility.Reprod Biol Endocrinol.2018;16(1):22. doi:10.1186/s12958-018-0336-z
Lopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM.Hormonal contraceptives for contraception in overweight or obese women.Obstet Gynecol.2010;116(5):1206-7. doi:10.1097/AOG.0b013e3181f81ccf
Westhoff CL, Torgal AH, Mayeda ER, et al.Ovarian suppression in normal-weight and obese women during oral contraceptive use: a randomized controlled trial.Obstet Gynecol.2010;116(2 Pt 1):275-83. doi:10.1097/AOG.0b013e3181e79440
Lopez LM, Bernholc A, Chen M, et al.Hormonal contraceptives for contraception in overweight or obese women.Cochrane Data System Rev.2016 Aug 18:(8):CD008452. doi:10.1002/14651858.CD008452.pub4
Robinson JA, Burke AE.Obesity and hormonal contraceptive efficacy.Womens Health (Lond).2013;9(5):453-66. doi:10.2217/whe.13.41
Mody SK, Han M.Obesity and contraception.Clin Obstet Gynecol.2014;57(3):501-7. doi:10.1097/GRF.0000000000000047
Solymoss S.Risk of venous thromboembolism with oral contraceptives.CMAJ. 2011;183(18):E1278-9. doi:10.1503/cmaj.111614
Hee L, Kettner LO, Vejtorp M.Continuous use of oral contraceptives: an overview of effects and side-effects.Acta Obstet Gynecol Scand.2013;92(2):125-36. doi:10.1111/aogs.12036
Hales CM, Carroll MD, Fryar CD, Ogden CL.Prevalence of obesity among adults and youth: United States, 2015-2016.NCHS Data Brief. 2017 Oct;288:1-7.
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